First two series are meh. Worth watching for standout performances by Dean Stockwell and Star Trek veteran Jeffrey Coombs (Brunt, Weyoon) as Andorian Commander Shran. Berman had gone completely nuts at this point and Paramount kicked him upstairs putting Manny Coto in charge for series three which was fantastic but too late to save the series. In a Mirror, Darkly is without doubt the finest Enterprise has to offer and by the name I can assume you realize it's a Mirror universe episode. Alternate Intro
I'm probably being harsh on Kate Mulgrew as Janeway. I just feel she never really cared about the role. It's like Christoper Eccleston as The Doctor. He's a fine actor and did a very good job but you could tell it's just a job to him. David Tennant is nowhere near as good an actor but he had a genuine enthusiasm for the role that Eccleston didn't. Similarly while Shatner, Stewart and Brooks absolutely became their respective Captains, Mulgrew didn't. She was just jobbing in a role she cared little about. Probably due to the fact she was not first choice, Geneviéve Bujold was.

Stargate SG-1 is awsomesauce. It's a really good beginner Sci-Fi as Jack O'Neill is our everyman.
Doctor Who is more of a fantasy than a real Sci-Fi show.
Babylon 5 is magnificent but you will need to look past the slightly ropey effects.
Farscape is worth looking into if you like your Sci-Fi with a lot of humor and very little actual science.
Deep Space Nine is the best Star Trek has to offer.
Short series but amazing is Space, Above & Beyond. You will be annoyed at the cliffhanger ending though.
Andromeda is a baby of Gene Roddenberry, very quirky and a lot of cameos but good fun. Think of it as Hercules in Space.
Brit series to recommend is Ultraviolet. No not the horrible movie. It's only 6 episodes long but was magnificent television. Also Jack Davenport before Pirates of the Caribbean.

Nice, thanks for this list.

Voyager in my mind ruined many of the good things in Star Trek:
-Borg made into a generic villain race with queenie in every episode, faceless enemy was better. Zombie films always fail when they try to humanise the zombies, they are a force of (un)nature and the borg were a force of science, thats how they best work.
-Q was butchered. He does not work for anyone but Picard really, but for some reason they had to have Janeway 'changing' the Q, and when they bought in 'Q weapons' that apparently anyone can use to kill Q, I just facepalmed. Continuity errors ahoy in the changes they made with the Q in Voyager, and Q's apparent lust for Janeway was just dire and pointless.
-the Technobabble. Prime example, one of the episodes had Torres and Janeway hurl technobabble at each other about how to escape a black hole, and when one of the others asked for an explanation, instead of giving a layman's analogue like in the other Star Treks ("Like blowing up a ballon!" - Fry Futurama) they just waved "Its too advanced to explain"... I'm sorry but they can fuck off if they are not going to bother actually coming up with a decent explanation, thats just lazy writing. Off they go in a shuttlecraft for a jolly talk and then everything is fixed. Voyager was by far the worst for this out of all the Star Trek series, and shows the quality (lack of) of the writing at its finest. A prime example of "A Wizard Did It!" in a sci-fi program.
Now, onto the things that didn't work:
-lack of continuity. The other Star Treks did not have it either but by the time Voyager came out we had already had Babylon 5 and Buffy with their overarching plotlines that carried over from episode to episode, and so the self-contained episodes of the earlier Treks was a sign that the franchise had failed to keep up with the times. Voyager would be nearly destroyed and be heavily damaged at the end of one episode only to be back in tip top condition at the start of the next. Sure they had the 'get back to earth' plotline, but that was just an excuse for them to move on to the next adventure, the romances do not constitute a full overarching plot. This is supported by many of the writers themselves, as a whole bunch of them left to go write BSG after two weeks, complaining that Voyager had 'lied to the fans' for this very reason.
-Janeway. She was in no way a captain, she lacked any presence or skill at authority, and the actress seemed wooden to me. I could not feel anything for her, I'm sorry.
-Kes and Neelix. Two of the most boring, bland characters that were completely unnecessary to any plot I have ever seen. Worse than Jacob from ME2.

More smoke monsters, less tribbles... thread hijackers

There are two LOST threads. If threads could not be hijacked this would be a far less interesting place. Going off on a tangent is part of the GOG experience.